The aims of this thesis were firstly to review several techniques used to assess venous calf muscle pump function and to establish the relative importance of venous incompetence in different sites. Secondly to investigate venous elasticity in varicose limbs using a new method and thirdly to examine the effect of compression stockings on venous elasticity and venous valvular function.;Ambulatory venous pressure measurement showed strong agreement with the clinical severity of venous disease. The use of narrow tourniquets in combination with this technique was not helpful however in predicting the effect of venous surgery, indeed the technique did not differentiate deep from superficial reflux. Duplex scanning demonstrated that the tourniquets did not obstruct superficial venous flow as previously claimed. Air-plethysmography failed to distinguish between patients with venous disease of varied severity nor did the volume measurements agree with pressure measurement as previously claimed.;Statistical analysis of reflux patterns in 274 limbs found popliteal reflux to have the greatest clinical importance, followed by long saphenous reflux. Venous elasticity measurement showed reduced elasticity in varicose limbs at low distension pressures. Major surgery did not alter venous elasticity, but compression stockings produced an improvement. Duplex scanning showed that compression stockings reduced venous reflux but did not restore competence to incompetent veins.;In conclusion, ambulatory venous pressure remains the reference standard test of venous calf muscle pump function. The addition of tourniquets is unhelpful as is air-plethysmography. The popliteal and the long saphenous veins are the most important when considering a mixed pattern of venous reflux. Varicose veins show a defect in venous elasticity which is improved by elastic compression stockings, however in spite of reducing reflux the stockings do not restore venous valves to competence.